Distractor with removable footplates

ABSTRACT

A bone distractor assembly configured to distract first and second bone segments on opposite sides of a bone gap is provided. In one embodiment the distractor assembly includes a distractor having a first coupler and a second coupler, a first footplate releasably coupled to the first coupler, a second footplate releasably coupled to the second coupler, and a locking mechanism releasably coupling the first and second footplates to the first and second couplers. The first and second footplates releasably are each configured to attach to bone. The locking mechanism includes a tube, wherein removal of the tube releases the first and second footplates from the first and second couplers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/890,026filed Sep. 24, 2010, which claims the benefit of U.S. provisionalapplication 61/245,561 filed Sep. 24, 2009, the contents of which areincorporated by reference in their entirety.

BACKGROUND

Various developmental disorders of the human skull result incraniofacial abnormalities in which certain bones fail to grow in properproportion to other bones, or in which certain bones fuse prematurely,causing malformation of the mid-face or mandible. For example, onedisorder, Pierre Robin Sequence (PRS) is a complex condition in whichinfants are born with a micrognathic and/or retrognathic mandible thatcauses glossoptosis, resulting in respiratory distress. Mandibulardistraction is a treatment option, in which the mandible is advancedanteriorly, thereby pulling the tongue forward and opening up theairway.

A chief complaint among surgeons who use internal mandible distractorsto treat infants with certain disorders such as PRS is that somedistractors require a second surgical procedure for removal. The removalprocedure is difficult for several reasons: (1) the locations of thefootplates change during the course of treatment making them difficultto access through the same incision that was used for distractorimplementation, and (2) soft and hard tissue grows over the bone screwsduring treatment making it difficult to engage the screwdriver bladeinto the screw recess for removal.

Distractors that use resorbable footplates have been used to avoid thesecond surgical procedure, however, there have been complaints with thecurrent distractors that are used. For example, one distractor consistsof a metallic drive screw with a metallic activation extension thatengages two resorbable footplates, and can be detached by externallyreversing the metallic drive screw at the end of the consolidation phaseand removing it through the percutaneous activation port. Such adistractor has reportedly had problems with strength and bone segmentstability.

SUMMARY

Bone distractor assemblies configured to distract and/or reduce firstand second bone segments on opposite sides of a bone gap are provided.In one embodiment the distractor assembly includes a distractor having afirst coupler and a second coupler, a first footplate configured to bereleasably engaged to the first coupler, and a second footplateconfigured to be releasably engaged to the second coupler. The first andsecond footplates are configured to attach to bone. The assembly furtherincludes a locking mechanism including a tube that is movable withrespect to the distractor between a locked position and a releasedposition. When the tube is in the locked position, the tube maintainsthe first and second footplates in engagement with the first and secondcouplers, respectively. When the tube is in the unlocked position, thefirst and second footplates are disengaged from the first and secondcouplers, respectively. The assembly further includes a release actuatorthat extends through the tube and is operably coupled to the distractor,such that movement of the release actuator to a removal position causesthe distractor to be removed from the first and second footplates.

In another embodiment the distractor assembly includes a firstfootplate, a second footplate translatably coupled to the firstfootplate, and a distractor releasably coupled to the first footplate.The second footplate includes an extension that carries a track. Thedistractor is releasably coupled to the first footplate and includes anactivation worm and a sleeve. The activation worm is configured toengage the track, such that rotation of the worm causes the secondfootplate to translate relative to the first footplate. The sleeveincludes a distal coupling portion that is configured to releasably lockthe activation worm to the first footplate.

In another embodiment the distractor assembly includes a distractor, afirst footplate releasably coupled to the distractor, and a secondfootplate releasably coupled to the distractor. The first and secondfootplates each have a central bridge portion that includes a pair ofprotrusions that define a recess therebetween. The distractor includes abody defining a bore, a pair of barrels disposed within the bore of thebody, and a pair of rails disposed about the body. Each barrel includesa protrusion that extends through a slot of the body and engages arecess of a respective footplate. Each rail is configured to selectivelyengage the protrusions of the first and second footplates to therebyreleasably attach the footplates to the distractor.

In another embodiment, the distractor assembly includes a first coupler,a second coupler, first footplate releasably coupled to the firstcoupler, and a second footplate releasably coupled to the secondcoupler. The first and second couplers each have a footplate couplingportion and a distractor connecting portion rotatably coupled to thefootplate coupling portion. Rotation of the distractor connectingportions of the first and second couplers locks the first and secondfootplates to the first and second couplers.

In another embodiment the distractor assembly includes a distractorhaving a first coupler and a second coupler, a first footplatereleasably coupled to the first coupler, and a second footplatereleasably coupled to the second coupler. The assembly further includesan activation mechanism having an activation worm that extends into atleast the first coupler. The activation mechanism defines a bore thatextends therethrough. The assembly further includes a sleeve disposedabout the activation mechanism and engagable with the first coupler, anda wire that extends through the bore of the activation mechanism.Disengagement of the sleeve from the first coupler releases the firstfootplate from the first coupler, and translation of the wire proximallypulls the distractor away from the first and second footplates.

In another embodiment the distractor assembly includes a firstfootplate, a second footplate, a coupler and a locking mechanism. Thefirst footplate includes a distally extending track. The secondfootplate includes a central bridge portion that is configured toreceive the track of the first footplate. The coupler is releasablycoupled to the central bridge portion of the second footplate. Thelocking mechanism is configured to releasably lock the coupler to thecentral bridge portion of the second footplate. The locking mechanismincludes a sleeve that defines threads, a nut that is threadably engagedwith the threads of the sleeve, and a locking component coupled to thenut. The locking mechanism is configured to have a first position inwhich the locking component engages the coupler to thereby lock thecoupler to the central bridge portion of the second footplate, and asecond position in which the locking component is disengaged from thecoupler to thereby release the coupler from the second footplate.

In another embodiment the distractor assembly includes a firstfootplate, a second footplate, a first coupler releasably coupled to thefirst footplate, and a second coupler releasably coupled to the secondfootplate. The first and second footplates each include a central bridgeportion. The first coupler includes a spring finger that is configuredto engage the central bridge portion of the first footplate. The secondcoupler includes a spring finger that is configured to engage thecentral bridge portion of the second footplate. The assembly furtherincludes a sleeve that is configured to slide over the first and secondcoupler's to thereby disengage the spring fingers from the centralbridge portions and release the first and second footplates from thefirst and second couplers.

In another embodiment the distractor assembly includes a distractor, afirst footplate, a second footplate, and a double barrel pin releasablycoupling the first and second footplates to the distractor. Thedistractor includes a first coupler, a second coupler, and a thirdcoupler. Each of the first, second and third couplers, defines a pair ofcoaxial bores. The first footplate has a central bridge portion thatdefines a pair of coaxial bores that align with the bores of the firstcoupler. The second footplate has a central bridge portion that definesa pair of coaxial bores that align with the bores of the second coupler.The double barrel pin is configured to extend through the bores of thefirst coupler, the bores of the second coupler, the bores of the thirdcoupler, and the bores of the first footplate, and the bores of thesecond footplate to thereby releasably lock the first and secondfootplates to the first and second couplers. Removal of the pin releasesthe first and second footplates from the first and second couplers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top plan view of a distractor assembly according to oneembodiment. The assembly includes a distractor, first and secondfootplates releasably coupled to the distractor, and a locking mechanismthat includes a tube that when removed releases the first and secondfootplates from the distractor;

FIG. 1B is a side cross sectional view of the distractor assembly shownin FIG. 1A through the line 1B-1B;

FIG. 1C is a top plan view of the distractor of the distractor assemblyshown in FIG. 1A;

FIG. 1D is a side elevational view of the distractor shown in FIG. 1C;

FIG. 1E is a top plan view of the first and second footplates of thedistractor assembly shown in FIG. 1A;

FIG. 1F is a side elevational view of the first and second footplatesshown in FIG. 1E;

FIG. 1G is cross-sectional view of the distractor assembly of FIG. 1A,showing the locking mechanism engaging the distractor and footplates tothereby lock the footplates to the distractor;

FIG. 2A is a top plan view of a distractor assembly according to anotherembodiment. The assembly includes a first footplate, a second footplatetranslatably coupled to the first footplate, and an activation mechanismthat is releasably coupled to the first footplate;

FIG. 2B is a side cross sectional view of the distractor assembly shownin FIG. 2A through the line 2B-2B;

FIG. 2C is an enlarged perspective view of a distal end of theactivation mechanism of the distractor assembly shown in FIG. 2A;

FIG. 2D is an enlarged perspective view of the distractor assembly shownin FIG. 2A, showing the second footplate coupled to the first footplate;

FIG. 3A is a top plan view of a distractor assembly according to anotherembodiment. The assembly includes a first footplate, a second footplatetranslatably coupled to the first footplate, and an activation mechanismthat is releasably coupled to the first footplate;

FIG. 3B is a side cross sectional view of the distractor assembly shownin FIG. 3A through the line 3B-3B;

FIG. 4 is a side elevational view of a distractor assembly according toanother embodiment. The assembly includes first and second footplatesreleasably coupled to first and second couplers by a locking mechanismincluding a tube that when removed releases the footplates from thecouplers;

FIG. 5A is a top plan view of a footplate that can be used with thedistractor assembly shown in FIG. 4;

FIG. 5B. is a front elevational view of the footplate shown in FIG. 5A;

FIG. 5C is a bottom plan view of the footplate shown in FIG. 5A;

FIG. 5D is a bottom plan view of two of the footplates shown in FIG. 5Areleasably coupled to respective couplers;

FIG. 5E is a bottom plan view of a footplate according to anotherembodiment, the footplate along with a footplate similar to thefootplate shown in FIG. 5A releasably coupled to respective couplers;

FIG. 6A is a perspective view of the first coupler of the distractorassembly shown in FIG. 4;

FIG. 6B is a back elevational view of the first coupler shown in FIG.6A;

FIG. 6C is a front elevational view of the first coupler shown in FIG.6A;

FIG. 6D is a bottom plan view of the first coupler shown in FIG. 6A;

FIG. 6E is a cross sectional view of the first coupler shown in FIG. 6Athrough the line 6E-6E;

FIG. 7A is a perspective view of the second coupler of the distractorassembly shown in FIG. 4;

FIG. 7B is a front elevational view of the second coupler shown in FIG.7A;

FIG. 7C is a back elevational view of the second coupler shown in FIG.7A;

FIG. 7D is a bottom plan view of the second coupler shown in FIG. 7A;

FIG. 7E is a cross sectional view of the second coupler shown in FIG. 7Athrough the line 7E-7E;

FIG. 8A is a perspective view of the distractor assembly shown in FIG.4, showing the locking mechanism locking the footplates to thedistractor;

FIG. 8B is a perspective view of the distractor assembly shown in FIG.8A, showing a tube portion of the locking mechanism being removed;

FIG. 8C is a bottom perspective view of the distractor assembly shown inFIG. 8A, showing the tube portion fully removed;

FIG. 9 is a top plan view of a locking mechanism according to anotherembodiment that may be used with a distractor assembly, the lockingmechanism including a double barrel pin having a flared end;

FIG. 10A is a side elevational view of a distractor assembly accordingto another embodiment. The assembly including first and secondfootplates releasably coupled to first and second couplers by a lockingmechanism that includes a double barrel pin releasably coupled to athird coupler;

FIG. 10B is a cross-sectional view of the distractor assembly shown inFIG. 10A through the line 10B-10B;

FIG. 10C is a cross-sectional view of the distractor assembly shown inFIG. 10A through the line 10C-10C;

FIG. 10D is a cross-sectional view of the assembly shown in FIG. 10Ashowing the double barrel pin engaging the footplates and the couplers;

FIG. 11A is a perspective view showing a distractor assembly accordingto another embodiment. The assembly including first and second couplersthat are releasably coupled to first and second footplates with springfingers having feet that engage slots defined by the footplates;

FIG. 11B is a front perspective view of the first coupler of thedistractor assembly shown in FIG. 11A;

FIG. 11C is a top perspective view of a footplate used in the distractorassembly shown in FIG. 11A;

FIG. 12A is a side elevational view of a distractor assembly accordingto another embodiment. The assembly including first and secondfootplates releasably coupled to first and second couplers with alocking mechanism that includes a locking pin, and a tube that whenremoved releases the first and second footplates from the distractor;

FIG. 12B is a front elevational view showing the engagement of the firstcoupler and the first footplate of the distractor assembly shown in FIG.12A;

FIG. 12C is a side cross-sectional view of the distractor assembly shownin FIG. 12A;

FIG. 12D is a top cross-sectional view of the distractor assembly shownin FIG. 12A;

FIG. 12E is a partial side perspective view of a locking portion of thelocking pin of the distractor assembly shown in FIG. 12A;

FIG. 12F is a front elevational view of the locking portion shown inFIG. 12E;

FIG. 13A is a top cross-sectional view of a distractor assemblyaccording to another embodiment. The assembly including a firstfootplate, a second footplate translatably coupled to the firstfootplate, and an activation mechanism that is releasably coupled to thefirst footplate;

FIG. 13B is a front perspective view of a retaining clip of a worm gearof the activation mechanism shown in FIG. 13A;

FIG. 13C is a front cross-sectional view of the distractor assemblyshown in FIG. 12A through the line 13C-13C;

FIG. 14A is top plan view of a distractor assembly according to anotherembodiment. The assembly including first and second footplatesreleasably coupled to a distractor using L-rails that are configured tocompress upon the attachment of an activation mechanism;

FIG. 14B is a side elevational view of the distractor assembly shown inFIG. 14A;

FIG. 14C is a top cross-sectional view of the distractor assembly shownin FIG. 14A;

FIG. 14D is a partial side cross-sectional view of the distractorassembly shown in FIG. 14A, showing the activation extension engagingthe distractor L-rail;

FIG. 14E is a front cross-sectional view of the assembly shown in FIG.14A, showing the L-rails engaging the footplate;

FIG. 14F is a front cross-sectional view of the assembly shown in FIG.14A, showing the L-rails disengaged from the footplate;

FIG. 15A is a top plan view of a distractor assembly according toanother embodiment. The assembly including a distractor with twocoupling assemblies that releasably attach the distractor to respectivefootplates;

FIG. 15B is a side elevational view of a third coupling attached to thedistractor shown in FIG. 15A, the third coupling being configured toallow an activation mechanism to selectively rotate the first and secondcouplings;

FIG. 15C is a side cross-sectional view of the first coupling shown inFIG. 15A including a screw lock that prevents unwanted rotation of thedistractor;

FIG. 15D is a front cross-sectional view of the first coupling of thedistractor assembly shown in FIG. 15A in a locked position therebykeeping the footplates attached to the assembly;

FIG. 15E is a front cross-sectional view of the first coupling of thedistractor assembly shown in FIG. 15D in an unlocked position therebyallowing the footplate to be detached from the assembly;

FIG. 16A is a top plan view of a distractor assembly according toanother embodiment, the assembly including a distractor attached to afootplate with a resorbable screw;

FIG. 16B is a partial view of the distractor assembly shown in FIG. 16Ashowing the screw;

FIG. 17A is a perspective view of a distractor assembly according toanother embodiment. The assembly including a distractor having areleasable stop that selectively couples first and second footplates tothe distractor;

FIG. 17B is a side cross-sectional view of the assembly shown in FIG.17A, with the releasable stop in a closed position;

FIG. 17C is a partial side cross-sectional view of the assembly shown inFIG. 17A with the releasable stop in an open position;

FIG. 17D is a top plan view of the first and second footplates of theassembly shown n FIG. 17A;

FIG. 17E is a side elevational view of the first and second footplatesshown in FIG. 17D;

FIG. 18A is a perspective view of a distractor assembly that is similarto the assembly shown in FIG. 17A except that the releasable stop is ascrew that releases from the distractor body when a tube is pulledproximally;

FIG. 18B is a perspective view of the distractor assembly of FIG. 18Awith the tube pulled proximally and disengaged from the screw;

FIG. 19A is a top plan view of a distractor assembly according toanother embodiment. The assembly including a distractor having adistractor body that releasably holds first and second footplates to thedistractor body when an activation mechanism is releasably attached tothe distractor body;

FIG. 19B is a side elevational view of the distractor assembly shown inFIG. 19A;

FIG. 19C is a cross-sectional view of the distractor assembly shown inFIG. 19B through the line 19C-19C;

FIG. 19D is a side cross-sectional view of the distractor assembly shownin FIG. 19A;

FIG. 19E is a side elevational view of the first and second footplatesof the distractor assembly shown in FIG. 19A;

FIG. 19F is a top plan view of the first and second footplates shown inFIG. 19E;

FIG. 19G is a front elevational view of the first and second footplatesshown in FIG. 19E;

FIG. 20A is a perspective view of the distractor assembly shown in FIG.19A including a distractor having a curved track;

FIG. 20B is a cross-sectional view of the distractor assembly shown inFIG. 20A;

FIG. 21A is a perspective view of a distractor assembly according toanother embodiment. The assembly including a distractor and first andsecond footplates releasably coupled to the distractor with a lockingmechanism having a tube that when removed releases the footplates fromthe distractor;

FIG. 21B is a side elevational view of the distractor assembly shown inFIG. 21A;

FIG. 21C is a side cross-sectional view of the distractor assembly shownin FIG. 21B;

FIG. 21D is a top plan view of the distractor of the distractor assemblyshown in FIG. 21A without the footplates attached to it;

FIG. 21E is a bottom plan view of the distractor shown in FIG. 21Dwithout the footplates attached to it;

FIG. 21F is a top plan view of the first and second footplates of thedistractor assembly shown in FIG. 21A;

FIG. 21G is a side elevational view of the first and second footplatesshown in FIG. 21F;

FIG. 21H is a front elevational view of the second footplate shown inFIG. 21F;

FIG. 21I is a front elevational view of the first footplate shown inFIG. 21F;

FIG. 22A is a perspective view of a distractor assembly according toanother embodiment. The assembly including a distractor, first andsecond footplates, and a locking mechanism that includes a sleeve, a nutthreadably engaged with the sleeve and a locking component configured toselectively engage a coupler and the first footplate to thereby lock thefootplates to the distractor;

FIG. 22B is a cross-sectional view of the distractor assembly shown inFIG. 22A;

FIG. 22C is a front perspective view of the first footplate and couplerof the distractor assembly shown in FIG. 22A;

FIG. 22D is a front elevational view of the distractor assembly shown inFIG. 22A;

FIG. 22E is a side elevational view of the distractor assembly shown inFIG. 22A with the locking component engaged with the coupler and thefirst footplate;

FIG. 22F is a side elevational view of the distractor assembly shown inFIG. 22E with the locking component disengaged from the coupler and thefirst footplate;

FIG. 22G is a top plan view of the first and second footplates of thedistractor assembly shown in FIG. 22A; and

FIG. 22H is a bottom plan view of the first and second footplates shownin FIG. 22G.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIGS. 1A-1G show an embodiment of a distractor assembly that isconfigured to correct certain craniofacial abnormalities. As shown, adistractor assembly 10 is elongate in a longitudinal direction L andincludes a distal end D and a proximal end P. As shown, the distractorassembly 10 includes a distractor 14, a first footplate 18 releasablycoupled to the distractor 14, and a second footplate 22 releasablycoupled to the distractor 14 at a location distal to the first footplate18. Generally, the distractor assembly 10 operates by affixing theseparate footplates 18 and 22 to first and second bone segments onopposite sides of a bone gap. The bone gap can be a fracture created bya traumatic event, an osteotomy, or can be the result of debridement ofa joint of two discrete bones to be joined in an arthodesis. After awaiting period, following implantation of the distractor assembly 10,one of or both of the footplates 18, 22 are translated relative to theother to thereby drive the bones on either side of the bone gap awayfrom each other. After the desired amount of distraction is achieved,another waiting period is required to allow the new bone growth tobecome sufficiently consolidated. Subsequently, the distractor 14 isremoved. It may be preferred that the footplates 18 and 22 are made froma resorbable material. If such materials are used, the footplates 18 and22 can be left behind and will resorb into the bone. The footplates 18and 22 may also be made from a flexible material.

As shown in FIGS. 1C-1D, the distractor assembly 10 includes adistractor 14 having a distractor body 34 that is releasably coupled tothe first and second footplates 18, 22, and an activation mechanism 38that is configured to translate the second footplate 22 distallyrelative to the first footplate 18. The distractor assembly 10 furtherincludes a locking mechanism 42 configured to selectively couple thedistractor body 34 to the first and second footplates 18, 22. As shown,the distractor 14 is elongate in the longitudinal direction L anddefines a central axis A extending between the proximal and distal endsof the distractor 14. The distractor 14 is generally made frombio-compatible materials.

As best shown in FIGS. 1C and 1D, the distractor body 34 includes afirst body portion 50 and a second body portion 54 that is configured totranslate distally relative to the first body portion 50. As shown, thefirst body portion 50 is elongate in the longitudinal direction L andincludes an elongate channel 58 that extends through the body portion 50in the longitudinal direction L. The first body portion 50 thereforedefines, or the channel 58, is otherwise defined by two verticallyextending side walls 62. As shown in FIG. 1C, a recess or groove 66extends along an upper end of each side wall 62 in the longitudinaldirection L along a major portion of the longitudinal length of thefirst body portion 50. The recesses 66 are configured to receive aportion of the second body portion 54 to allow the second body portion54 to translate relative to the first body portion 50 while at the sametime remaining aligned with the first body portion 50.

Each side wall 62 further defines a spring finger 72 proximate to thedistal ends of the side walls 62. As best shown in FIG. 1G, the springfingers 72 each include an outward extending protrusion 76 at itsrespective end. That is, each finger 72 includes a protrusion 76 thatextends laterally away from the central axis of the distractor 14. Thefingers 72 are configured to spring out and engage the first footplate18 to thereby couple the first footplate 18 to the first body portion50. In this way, the first body portion 50 may be considered a firstcoupler for coupling the first footplate 18 to the distractor 14.

The second body portion 54 is also elongate in the longitudinaldirection L and includes a holding portion 82 and an activation track 86that extends proximally from the holding portion 82. The holding portion82 includes side walls 94 that define an elongate channel 98 thatextends through the holding portion 82 in the longitudinal direction L.The channel 98 of the second body portion 54 is aligned with the channel58 of the first body portion 50. Each side wall 94 defines a springfinger 102 proximate to the distal ends of the side walls 94. As bestshown in FIG. 1G, the spring fingers 102 each include an outwardextending protrusion 106 at its respective end. That is, each finger 102includes a protrusion 106 that extends laterally away from the centralaxis of the distractor 14. The fingers 102 are configured to spring outand engage the second footplate 22 to thereby couple the secondfootplate 22 to the second body portion 54. In this way, the second bodyportion 54 may be considered a second coupler for coupling the secondfootplate 22 to the distractor 14

The activation track 86 of the second body portion 54 extends out fromthe holding portion 82 and is configured to engage the recesses 66 ofthe first body portion 50. As shown in FIG. 1C, the activation track 86defines a plurality of grooves 110 that are exposed to the channel 58 ofthe first body portion 50. The grooves 110 are disposed along thelongitudinal length of the activation track 86 and are configured to beengaged by external threads defined by the activation mechanism 38.

As shown in FIGS. 1C and 1D, the distractor 14 includes an activationmechanism 38 for translating the second body portion 54 of thedistractor 14 and thus the second footplate 22 relative to the firstbody portion 50. The activation mechanism 38 is elongate in thelongitudinal direction L and extends into the channel 58 of the firstbody portion 50. As shown, the activation mechanism 38 includes an innersleeve 120 and an activation worm 124 coupled to a distal end of theinner sleeve 120. The inner sleeve 120 includes generally a tubular body128 defining a longitudinally elongate bore 132 that extends through thebody 128. The inner sleeve 120 further defines a coupling feature 129such as a hex at its proximal end. As shown, the proximal end of theinner sleeve 120 and thus the coupling feature 129 protrude from theproximal end of the first body portion 50. The protruding couplingfeature 129 is then capable of being engaged by a driver to therebyrotate or otherwise drive the activation mechanism 38.

The activation worm 124 coupled to the distal end of the inner sleeve120 generally includes a cylindrical body 133 defining a longitudinalbore 134 that extends therethrough, and external threads 136 about thebody's external surface. The bore 134 is aligned with the bore 132 ofthe inner sleeve 120. The external threads 136 are configured to engagethe plurality of grooves 110 of the second body portion's activationtrack 86. As the activation mechanism 38, and thus the activation worm124, are rotated, the second body portion 54 is translated with respectto the first body portion 50.

As shown in FIG. 1C, the activation mechanism 38 also includes an outersleeve 142 having a longitudinal bore 146 that extends therethrough. Asshown, the outer sleeve 142 is retained within a proximal end of thechannel 58 of the first body portion 50 and the inner sleeve 120 extendsinto and through the bore 146 of the outer sleeve 142. A portion of theouter sleeve 142 protrudes from the proximal end of the channel 58 ofthe first body portion 50 and defines a large diameter portion 150. Thelarge diameter portion 150 serves to keep the percutaneous port in whichthe distractor 14 is inserted at a large enough size that the distractor14 can pass through it during device removal. Both the inner sleeve 120and the outer sleeve 142 may be made from a flexible material to allowoff-axis activation of the distractor 14. Alternatively, the innersleeve 120 and the outer sleeve 142 may have a curvature and be made ofa rigid material. In such cases the inner sleeve 120 and the outersleeve 142 may be designed by laser cut.

The distractor assembly 10 further includes a locking mechanism 42configured to releasably couple the first and second footplates 18, 22to the distractor 14. In particular the locking mechanism 42 isconfigured to lock or otherwise engage the footplates 18, 22 to thedistractor 14 when in a locked position, and is configured to release orotherwise disengage the footplates 18, 22 from the distractor when in anunlocked position. As shown, the locking mechanism 42 extends througheach of the bore 132 of the inner sleeve 120, the bore 134 of theactivation worm 124, and the channel 98 of the second body portion 54.As shown, the locking mechanism 42 includes a tube 154 defining alongitudinally elongate bore 158 that extends therethrough, and aremoval actuator 162 that extends completely through the bore 158.Preferably the tube 154 is made from a shape memory material such asnitinol, and the actuator 162 is a wire made from a flexible materialsuch as titanium. A distal end of the actuator 162 includes an enlargedportion or ferrule 166 that has a diameter larger than the diameter ofthe second body portion's channel 98. A proximal end of the actuator 162protrudes from the proximal end of the tube 154 and also includes aferrule to thereby trap the tube 154 onto the actuator 162.

When in the locked position, the tube 154 of the locking mechanism 42forces the fingers 72, 102 of the first and second body portions 50, 54laterally outward such that the protrusions 76, 106 of the fingers 72,102 engage respective footplates 18, and 22 to thereby maintain thefootplates 18, 22 in engagement with the distractor 14. When in theunlocked position, the tube 154 is removed such that the fingers 72, 102spring inward and the protrusions 76, 106 disengage from the footplates18, 22 to thereby release or otherwise disengage the footplates 18, 22from the distractor 14. Once the footplates are disengaged from thedistractor 14 the actuator 162 may be moved (i.e. pulled) to therebyremove the distractor 14 from the footplates 18, 22 and leave thefootplates 18, 22 behind to resorb into the bone.

The first and second footplates 18, 22 that are to be releasably coupledto the distractor 14 are best shown in FIGS. 1A, 1B, 1E, 1F, and 1G. Asshown in FIGS. 1E and 1F, the first footplate 18 includes a pair ofwings 170 that extend laterally out from a central bridge portion 174.Each wing 170 is substantially planar and includes a plurality of screwholes 178 for receiving bone screws therethrough to secure the wings 170to bone, with wings 170 lying flat adjacent to the bone surface. 1.3 mmor 1.5 mm resorbable screws may be used to fasten the wings to bone.

The central bridge portion 174 includes a longitudinal channel 182 thatis configured to receive the distractor 14 as shown in FIG. 1A. Asshown, the channel 182 has a pair of opposing longitudinal sidewalls184. Each sidewall 184 includes a lateral aperture 185 that isconfigured to receive a protrusion 76 of a respective spring finger 72of the distractor first body portion 50 to thereby couple the firstfootplate 18 to the distractor 14, as shown in FIG. 1G. The bridgeportion 174 further includes a pair of leading ratchet tabs 186 thatextend proximally from a proximal surface 190 of the bridge portion 174,and a set of lagging ratchet tabs 194 that extend distally from a distalsurface 198 of the bridge portion 174.

The leading ratchet tabs 186 are configured to prevent inadvertentforward movement of the second footplate 22 with respect to the firstfootplate 18 after the distractor 14 has been removed. As shown in FIG.1E, each leading ratchet tab 186 extends from a lower portion of theproximal surface 190 on respective sides of the channel 182. Eachleading ratchet tab 186 includes a protrusion 202 at its proximal endthat protrudes inward toward a longitudinal central axis of the bridge174. In use, the tabs 186 flex and function as a ratchet with the secondfootplate 22.

The lagging ratchet tabs 194 are configured to prevent reverse slidingonce the second footplate 22 is translated relative to the firstfootplate 18. As shown, the lagging ratchet tabs 194 include a pair ofupper tabs 206 that extend down at an angle from the distal surface 198of the bridge portion 174, on respective sides of the channel 182. Thelagging ratchet tabs 194 further include a pair of lower tabs 208 thatextend up at an angle from the distal surface 198 of the bridge portion174, on respective sides of the channel 182. In use, the tabs 194 flexand function as a ratchet with the second footplate 22.

Also shown in FIGS. 1E and 1F, the second footplate 22 includes a pairof wings 210 that extend laterally out from a central bridge portion214. Each wing 210 is substantially planar and includes a plurality ofscrew holes 218 for receiving bone screws therethrough to secure thewings 210 to bone, with wings 210 lying flat adjacent to the bonesurface. 1.3 mm or 1.5 mm resorbable screws may be used to fasten thewings 210 to bone.

The central bridge portion 214 includes a longitudinal channel 222 thatis configured to receive the distractor 14 as shown in FIG. 1A. Asshown, the channel 222 has a pair of opposing longitudinal sidewalls224. Each sidewall 224 includes a lateral aperture 226 that isconfigured to receive a protrusion 106 of a respective spring finger 102of the distractor second body portion 54 to thereby couple the secondfootplate 22 to the distractor 14, as shown in FIG. 1G.

The second footplate 22 further includes a longitudinally elongateextension 230 that extends proximally from a proximal surface 234 of thecentral bridge portion 214. As shown in FIG. 1F, the extension 230extends from the central bridge portion 214 below the channel 222 andextends through the channel 182 of the first footplate's central bridgeportion 174. The extension 230 defines opposing lateral sides 240, andopposing upper and bottom surfaces 244, 248 respectively. Each side 240defines engagement features, such as teeth 252 that are configured toengage the protrusions 202 of the first footplate's leading ratchet tabs186. The upper surface 244 and the bottom surface 248 also defineengagement features, such as teeth 256 that are configured to engage thelagging ratchet tabs 194. In particular, the upper surface 244 includestwo rows of teeth that are configured to engage the upper tabs 206, andthe bottom surface 248 includes two rows of teeth 252 that areconfigured to engage the lower tabs 208.

In operation, the distractor assembly 10 is inserted and the first andsecond footplates 18, 22 are attached to bone on opposite sides of abone gap. After a waiting period, following implantation of thedistractor assembly 10, the second footplate 22 is translated relativeto the first footplate 18 to thereby drive the bones on either side ofthe bone gap away from each other. The second footplate 22 is translatedby rotating the activation mechanism 38. When the activation mechanism38 is rotated, the external threads 136 of the activation worm 124engage the angled grooves 110 of the distractor second body portion 54to thereby drive the second body portion 54 distally away from the firstbody portion 50. This is done until the desired separation of thefootplates 18, 22 is achieved.

At the time of distractor removal, the surgeon will cut off the proximalferrule of the locking mechanism's actuator 162 that extends proximallyfrom the distractor 14 and through the patient's skin with a pair ofwire cutters. Once the proximal ferrule is cut, the tube 154 may beremoved leaving only the actuator 162 between the body portions 50, 54and respective footplates 18, 22, which is not of sufficient diameter toprevent deflection of fingers 72, 102. Therefore, the fingers 72, 102are no longer engaged with the apertures 185, 226 of the first andsecond footplates 18, 22, and thus the first and second footplates 18,22 are released or otherwise disengaged from the distractor 14. Then bymoving (i.e. pulling) the actuator 162 to a removal position, thesurgeon will remove the distractor 14 from the detachable footplates 18,22, leaving only the detachable footplates 18, 22 still attached to thepatient. Removal of the distractor 14 will be accomplished through thepercutaneous port that the locking mechanism 42 extended through.

Because the detachable footplates are left behind, they preferably aremade from a resorbable material, which will resorb over a 1-2 yearresorption period. It is intended, however, that the detachablefootplates 18, 22 can be titanium.

In another embodiment, and in reference to FIGS. 2A-2D the distractorassembly may include an activation mechanism that directly engages thesecond footplate to thereby translate the second footplate relative tothe first footplate. As shown, a distractor assembly 310, includes adistractor 314, a first footplate 318 releasably coupled to thedistractor 314, and a second footplate 322 translatably coupled to thefirst footplate 318. When the distractor 314 is rotated, the secondfootplate 322 is translated distally relative to the first footplate318.

As shown in FIG. 2B, the distractor 314 includes an activation mechanismthat is defined by a longitudinally elongate body 326. In this regardthe body 326 includes a coupling member 330 at its proximal end and anactivation worm 334 at its distal end. The coupling member 330 may be ahex coupling that is configured to connect to a driver so that thedistractor 314 may be rotated. The activation worm 334 extending fromthe distal end of the body 326 includes a distally extending conicalhead 338 having external threads 342. The external threads 342 areconfigured to engage the second footplate 322 to thereby translate thesecond footplate distally relative to the first footplate 318. Thedistractor 314 further includes a sleeve 346 that is disposed about thebody 326. A distal portion of the sleeve 346 defines a coupling portionthat includes external threads 350 configured to engage internal threadsdefined by the first footplate 318 to thereby couple the distractor 314to the first footplate 318. Proximate to the proximal end of thesleeve's threaded portion is an outwardly extending shoulder 354 that isconfigured to abut an outer surface of the first footplate 318 when thedistractor 314 is coupled to the first footplate 318.

As shown in FIGS. 2A-2B, and 2D, the distractor assembly 310 furtherincludes first and second footplates 318, 322 releasably coupled to thedistractor 314. The first footplate 318 is stationary with respect tothe distractor 314, while the second footplate 322 is translatable withrespect to both the distractor 314 and the first footplate 318.

As shown, the first footplate 318 includes a pair of wings 370 thatextend laterally out from a central bridge portion 374. Each wing 370 issubstantially planar and includes a plurality of screw holes 378 forreceiving bone screws therethrough to secure the wings 370 to bone, withwings 370 lying flat adjacent to the bone surface. 1.3 mm or 1.5 mmresorbable screws may be used to fasten the wings to bone.

The central bridge portion 374 of the first footplate 318 includes alongitudinal channel 382 that is configured to receive the distractor314 as shown in FIG. 2B. As shown, the channel 382 extends at an anglewith respect to the second footplate 322. Thus, the distractor 314extends out from the first footplate 318 at an angle. The central bridgeportion 374 further includes a second longitudinal channel 386 thatextends completely through the bridge portion 374 below the firstchannel 382. The second channel 386 is configured to receive a portionof the second footplate 322 and is at least partially exposed to thefirst channel 382 so as to allow the distractor 314 to engage the secondfootplate 322. The bridge portion 374 further includes a lagging ratchettab 394 that extends distally from a distal surface 398 of the bridgeportion 374.

The lagging ratchet tab 394 acts as a ratchet and is configured toprevent reverse sliding once the second footplate 322 is translatedrelative to the first footplate 318. As shown, the lagging ratchet tab394 extends down at an angle from the distal surface 398 of the bridgeportion 374. In use, the tab 394 flexes and functions as a ratchet withthe second footplate 322 as the second footplate 322 is translatedrelative to the first footplate 318.

As shown in FIGS. 2A-2B, the second footplate 322 includes a pair ofwings 410 that extend laterally out from a central bridge portion 414.Each wing 410 is substantially planar and includes a plurality of screwholes 418 for receiving bone screws therethrough to secure the wings 410to bone, with wings 410 lying flat adjacent to the bone surface. 1.3 mmor 1.5 mm resorbable screws may be used to fasten the wings 410 to bone.

The central bridge portion 414 of the second footplate 422 includes alongitudinally elongate extension 422 that extends proximally toward thefirst footplate 318. In particular, the extension 422 extends throughthe second channel 386 of the first footplate 318. As shown in FIG. 2D,an upper surface of the extension 422 includes a plurality of grooves426 that are configured to engage the external threads 342 of thedistractor 314. In this way the extension 422 carries a track.Additionally, the grooves 426 are configured to be engaged by the tab394 of the first footplate 318 to prevent reverse sliding of the secondfootplate 322 relative to the first footplate 318.

In operation, the distractor assembly 310 is inserted and the first andsecond footplates 318, 322 are attached to bone on opposite sides of abone gap. After a waiting period, following implantation of thedistractor assembly 310, the second footplate 322 is translated relativeto the first footplate 318 to thereby drive the bones on either side ofthe bone gap away from each other. The second footplate 322 istranslated by rotating the body 326. When the body 326 is rotated, theexternal threads 342 of the activation worm 334 engage the grooves 426of the second footplate 322 to thereby drive the second footplate 322distally away from the first footplate 318. This is done until thedesired separation of the footplates 318, 322 is achieved. At the timeof distractor 314 removal the surgeon will rotate the sleeve 346 of thedistractor 314 until the distractor 314 can be removed. The first andsecond footplates 318, 322 will remain behind and be resorbed into thebone.

In another embodiment and in reference to FIGS. 3A and 3B, thedistractor assembly may be similar to the embodiment shown in FIGS.2A-2D, but includes different structure for coupling the distractor tothe footplates, and ratchet tabs that engage teeth on opposing sides ofthe second footplates extension. As shown, a distractor assembly 430includes a distractor 434, a first footplate 438 releasably coupled tothe distractor 434, and a second footplate 442 translatably coupled tothe first footplate 438. The distractor 434 is similar to the distractordescribed in reference to FIGS. 2A-2D except that the distractor 434 iscoupled to the first footplate 438 using deflectable tabs. Likewise, thefirst and second footplates 438, 442, are similar but include differentstructure to prevent reverse sliding of the second footplate 442relative to the first footplate 438 after distraction has taken place.

In that regard, the distractor 434 includes an activation mechanism thatis defined by a longitudinally elongate body 443 and an activation worm444 extending distally from the body 443. A proximal end of the of worm444 includes a deflectable finger 445 that is configured to engage thefirst footplate 438. The distractor 434 further includes a sleeve 446that defines a distal coupling portion that defines internal threads 447that engage external threads defined by a distal portion of the body443. When the sleeve 446 is advanced distally, the finger 445 isdeflected to thereby couple or otherwise lock the distractor 434 to thefirst footplate 438. When the sleeve is retracted proximally, the finger445 is free to deflect and the distractor 434 may be pulled from thefirst footplate 438.

As shown in FIG. 3A, the first footplate 438 includes a pair of wings450 that extend laterally out from a central bridge portion 454. Thecentral bridge portion 454 includes a longitudinal channel 458 that isconfigured to receive the distractor 434 as shown in FIG. 3B. As shown,the channel 458 extends at an angle with respect to the second footplate442. Thus, the distractor 434 extends out from the first footplate 438at an angle. The central bridge portion 454 further includes a secondlongitudinal channel 462 that extends completely through the bridgeportion 454 below first channel 458. The second channel 462 isconfigured to receive a portion of the second footplate 442 and is atleast partially exposed to the first channel 458 so as to allow thedistractor 434 to engage the second footplate 442. The bridge portion454 further includes a pair of lagging ratchet tabs 468 that extenddistally from a distal surface 472 of the bridge portion 454.

The lagging ratchet tabs 468 act as a ratchet and are configured toprevent reverse sliding once the second footplate 442 is translatedrelative to the first footplate 438. As shown, the lagging ratchet tabsextend distally from the distal surface 472 of the bridge portion 454 oneither side of the second channel 462. Each tab 468 includes aprotrusion 476 that extends inward toward such that the protrusions 476of each tab 468 extends toward the other. In use, the tabs 468 flex andfunction as ratchets with the second footplate 442 as the secondfootplate 442 is translated relative to the first footplate 338.

As best shown in FIGS. 3A and 3B, the second footplate 442 includes apair of wings 480 that extend laterally out from a central bridgeportion 484. The central bridge portion 484 includes a longitudinallyelongate extension 488 that extends proximally toward the firstfootplate 438. In particular, the extension 488 extends through thesecond channel 462 of the first footplate 438. An upper surface of theextension 488 includes a plurality of grooves 492 that are configured toengage the external threads of the distractor 434. In this way theextension 488 defines a track. Furthermore, lateral side surfaces of theextension 488 define teeth 494 that are configured to be engaged by thetabs 468 of the first footplate 438 to prevent reverse sliding of thesecond footplate 442 relative to the first footplate 438.

In another embodiment and in reference to FIG. 4, the distractorassembly may include couplers that engage respective footplates toreleasably couple the footplates to the distractor. As shown, adistractor assembly 510 includes a distractor 514, a first footplate 518releasably coupled to the distractor 514, and a second footplate 522releasably coupled to the distractor 514 at a location that is distal tothe first footplate 518. In the embodiment shown, the first footplate518 is configured to translate proximally relative to the secondfootplate 522.

As shown in FIG. 4, the distractor 514 includes a longitudinallyelongate body 526, a first coupler 530 for releasably coupling the firstfootplate 518 to the distractor body 526, and a second coupler 534 forreleasably coupling the second footplate 522 to the distractor body 526.The distractor 514 further includes an activation mechanism 538 fortranslating the first footplate 518 relative to the second footplate522.

The distractor body 526 includes a longitudinally elongate channel 546that extends through the body 526. The channel 546 is configured toreceive the activation mechanism 538 as shown in FIG. 4. The body 526further defines a longitudinally elongate slot 550 that extends along atleast a portion of the body 526. In particular, the slot 550 extendsalong a bottom of the body 526 and provides access to the channel 546along its entire length. In that regard, the first coupler 530 extendsthrough the slot 550 and into the channel 546 and is coupled to theactivation mechanism 538 within the channel 546. The slot 550 thereforeallows the first coupler 530 to translate along the body 526 without anyinterference.

The first footplate 518 is best shown in FIGS. 5A-5C. As shown, thefirst footplate 518 includes a pair of wings 580 that extend out from acentral bridge portion 584. Each wing 580 is substantially planar andincludes a plurality of screw holes 588 for receiving bone screwstherethrough to secure the wings 580 to bone, with wings 580 lying flatadjacent to the bone surface. 1.3 mm or 1.5 mm resorbable screws may beused for example to fasten the wings 580 to the bone. Central bridgeportion 584 includes a body portion 590 and a pair of upwardly extendingprojections 592 that extend up from an upper surface of the body portion590 and terminate at an inward extending flange 596. As shown, theprojections 592 including the flanges 596 define a T-slot 600. The uppersurface of the body portion 590 defines a detent 604 proximate to itsdistal end.

The second footplate 522 may be identical to the first footplate shownin FIGS. 5A-5C, except that the second footplate may be oriented in anopposite direction than the first footplate 518, as shown in FIG. 5D.Alternatively, the second footplate 522 may be disposed at an end of thedistractor 514 and may include a single large wing 606, as shown in FIG.5E, as opposed to including a pair of wings.

As shown in FIGS. 4, and 6A-6E the first coupler 530 is configured toreleasably couple the first footplate 518 to the distractor body 526. Asshown in FIGS. 6A-6E, the first coupler 530 includes a distractorconnecting portion 608 and a footplate coupling portion 612 that isconnected to the distractor connecting portion 608 by a verticallyoriented pedestal 616. The connecting portion 608 includes alongitudinally elongate body 620 that defines a longitudinally elongatebore 624 that extends completely through the body 620. The bore 624includes internal threads that are configured to engage external threadsdefined by the activation mechanism 538. The direction of the threadsdefined by the bore 624 will depend on the direction the first footplate518 is to translate.

The footplate coupling portion 612 is configured to releasably connectto the first footplate 518 shown in FIGS. 5A-5C. As shown, the footplatecoupling portion 612 includes a body 630 that defines a bore 634 thatextends longitudinally through the body 630. A portion of the body 630that defines the bottom of the bore 634 defines a longitudinallyextending flexible finger 638 having a free end 642 to allow the finger638 to flex. As shown in FIG. 6D, a protrusion 646 extends down from abottom surface of the flexible finger 638 proximate to the free end 642of the finger 638. The protrusion 646 is configured to engage the detent604 defined in the bridge portion 584 of the first footplate 518. Thebody 630 further includes opposing outwardly extending flanges 650 thatextend along the longitudinal length of the body 630. As shown, the body630 and in particular the flanges 650 define a T-shape that isconfigured to engage the T-slot 600 defined by the first footplate 518.

To connect the first footplate 518 to the first coupler 530, the flanges650 of the first coupler 530 slidably engage the T-slot 600 of thefootplate 518. While the first footplate 518 is being slid into place,the flexible finger 638 will flex up as the protrusion 646 that extendsdown from the bottom surface of the finger 638 is dragged across theupper surface of the footplates central bridge portion 584. Once theprotrusion 646 of the finger 638 is positioned over the detent 604, thefinger 638 will return to its normal position, thereby placingprotrusion 646 into the detent 604. At this point, the first footplate518 is loosely held to the first coupler 530. To lock, the footplate 518to the first coupler 530 a locking mechanism, which will be discussedlater, extends through the footplate coupling portion's bore 634 tothereby force the protrusion 646 into the footplate detent 604, and lockthe footplate 518 to the first coupler 530.

As shown in FIGS. 4, and 7A-7E the second coupler 534 is configured toreleasably couple the second footplate 522 to the distractor body 526.As shown in FIGS. 7A-7E, the second coupler 534 includes a distractorconnecting portion 658 and a footplate coupling portion 662 that isconnected to the distractor connecting portion 658. The connectingportion 658 includes a body 670 that defines a cavity 674 that extendslongitudinally into the body 670. The cavity 674 is shown to berectangular in shape, and is configured to receive the body 526 of thedistractor 514. The back of cavity 674 includes a stop plate 682 havinga bore 686 therethrough. The stop plate 682 allows the second coupling534 to be securely placed onto the end of the distractor body 526. Inthis configuration, the second coupler 534, and thus the secondfootplate 522, are configured to remain stationary while the firstcoupler 530, and thus the first footplate 518 translate.

The footplate coupling portion 662 is configured to releasably connectto the second footplate 522. As shown, the footplate coupling portion662 includes a body 690 that defines a bore 694 that extendslongitudinally through the body 690. A portion of the body 690 thatdefines the bottom of the bore 694 defines a longitudinally extendingflexible finger 698 having a free end 702 to allow the finger 698 toflex. As shown in FIG. 7D, a protrusion 706 extends down from a bottomsurface of the flexible finger 698 proximate to the free end 702 of thefinger 698. The protrusion 706 is configured to engage a detent definedby the second footplate, similar to the detent 604 defined in the bridgeportion 584 of the first footplate 518. The body 690 further includesopposing outwardly extending flanges 710 that extend along thelongitudinal length of the body 690. As shown, the body 690 and inparticular the flanges 710 define a T-shape that is configured to engagea T-slot of the second footplate 522, similar to the T-slot 600 definedby the first footplate 518.

To connect the second footplate 522 to the second coupler 534, theflanges 710 of the second coupler 534 slidably engage the T-slot of thefootplate 522. While the second footplate 522 is being slid into place,the flexible finger 698 will flex up as the protrusion 706 that extendsdown from the bottom surface of the finger 698 is dragged across theupper surface of the footplates central bridge portion. Once theprotrusion 706 of the finger 698 is positioned over the detent, thefinger 698 will return to its normal position, thereby placingprotrusion 706 into the detent of the second footplate 522. At thispoint, the second footplate 522 is loosely held to the second coupler534. To lock, the footplate 522 to the second coupler 534 the lockingmechanism, which will be discussed later, extends through the footplatecoupling portion's bore 694 to thereby force the protrusion 706 into thesecond footplate's detent, and lock the footplate 522 to the secondcoupler 534.

As best shown in FIGS. 4, and 8A-8C the distractor assembly 510 furtherincludes a locking mechanism 542 that is movable between a lockedposition in which the first and second footplates 518, 522 aremaintained in engagement with the first and second couplers 530, 534,and an unlocked position in which the footplates 518, 522 are disengagedfrom the first and second couplers 530, 534. As shown, the lockingmechanism 542 extends through the bores 634, 694 of the first and secondcouplers 530, 534, and includes a tube 724 that defines a longitudinallyelongate bore 720, and a removal actuator 716 that extends through thebore 720. Preferably, the tube 724 is made from a shape memory material,such as nitinol, and the actuator 716 is a wire made from a flexiblematerial such as titanium. A distal end of the actuator 716 protrudesfrom the tube 724 and includes an enlarged portion or ferrule 728 thathas a diameter larger than the diameter of the second coupler's bore694. A proximal end of the actuator 716 also protrudes from the tube 724and includes a an enlarged portion or ferrule 732 to thereby trap thetube 724 between the two ferrules 728, 732.

When in the locked position, the tube 724 of the locking mechanism 542forces the fingers 638, 698 of the first and second couplers 530, 534outward such that the protrusions 646, 706 of the fingers 638, 698engage respective detents of the footplates 518, 522, to therebymaintain the footplates 518, 522 in engagement with the distractor 514.In other words, because the diameter of the tube 724 is large enough toprevent deflection of the fingers 638, 698, the protrusions 646, 706 ofthe fingers 638, 698 respectively, will remain in the detents of theirrespective footplates 518, 522, thereby preventing the distractor 514from separating from the footplates 518, 522. In use the lockingmechanism 542 lies passively in the soft tissue similar to theactivation mechanism 538.

At the time of distractor removal, the surgeon will cut off the proximalferrule 732 that extends through the patient's skin with a pair of wirecutters, allowing the tube 724 to be separated from the actuator 716 asshown in FIG. 8B. This will then leave only the actuator 716 between thefirst and second couplers 530, 534 and detachable footplates 518, 522,which is not of sufficient diameter to prevent deflection of the fingers638, 698. Then by moving (i.e. pulling) the actuator 716 to the unlockedposition, the surgeon will disengage the first and second couplers 530,534 from the detachable footplates 518, 522, leaving only the detachablefootplates 518, 522 still attached to the patient. Removal of thedistractor 514 will be accomplished through the percutaneous port thatthe locking mechanism 542 extends through.

Although it is preferred that the locking mechanism 542 extends from thepatient, it can also be attached so that locking mechanism 542 does notextend outside the patient. This prevents the patient from being able toaccess the locking mechanism 542 to cut it off prematurely, (which maycause the distractor to separate) but the surgeon would have to make anincision to gain access to it, at the time of removal. This may bepreferred for some surgeons who are willing to sacrifice anotherincision for greater security against premature separation.

FIG. 9 shows another locking mechanism that may be used to couple thefirst and second footplates to the first and second couplers. As shown,a locking mechanism 800 may be a solid pin 804 that extends beyond theoverall length of the distractor and remains buried under the softtissue. The end of this solid pin 804 may include a flare 808 so as toprevent separation under normal loads. At the time of distractorremoval, the surgeon would have to create an incision to re-expose thedistractor but would only have to access the pin 804 and pull it out,thereby allowing the distractor to separate from the footplates. Thismay allow for easier access to the bone screws in the area of thetemporomandibular joint during mandible distraction.

In another embodiment and in reference to FIGS. 10A-10D the distractorassembly may include a double barrel pin that releasably couples thefootplates to the distractor. As shown, the distractor assembly 810includes a distractor 814, a first footplate 818 releasably coupled tothe distractor 814, and a second footplate 822 releasably coupled to thedistractor 814 at a location distal to the first footplate 818. In theembodiment shown, the first footplate 818 is configured to translaterelative to the second footplate 822.

As shown in FIG. 10A, the distractor 814 includes a longitudinallyelongate body 826, a first coupler 830 for releasably coupling the firstfootplate 818 to the distractor body 826, a second coupler 834 forreleasably coupling the second footplate 822 to the distractor body 826,and a third coupler 840 for securing a locking mechanism 842 that isconfigured to lock the first and second footplates 818, 822 to the firstand second couplers 830, 834. As shown, the locking mechanism 842 is adouble barreled pin 846 having two longitudinally elongate barrels 848.The distractor 814 further includes an activation mechanism disposedwithin a channel of the body 826 for translating the first footplate 818relative to the second footplate 822

As shown in FIGS. 10B and 10D, the first and second footplates 818, 822each includes a pair of wings 850 that extend out from a central bridgeportion 854. Central bridge portion 854 includes a body portion 860 thatdefines a pair of longitudinally extending bores 864 that extendcompletely through the body portion 860. The bores 864 of each of thefirst and second footplates 818, 822 are configured to receive thelocking mechanism 842.

As shown in FIGS. 10A, 10B, and 10D, the first and second couplers 830,834 are configured to releasably couple the first and second footplates818, 822 to the distractor body 826. As shown, the first and secondcouplers 830, 834 each includes a respective distractor connectingportion 868 (that are similar to the distractor connecting portions 608,and 658, respectively, of the embodiment shown in FIGS. 4-8C) and afootplate coupling portion 862 connected to the distractor connectingportion 868. Because the distractor connecting portions 868 are similarto those described in relation to FIGS. 4-8C, the first coupler 830, andthus the first footplate 818 is configured to translate relative to thesecond coupler 834.

The footplate coupling portions 862 are configured to releasably connectto the first and second footplates 818, 822. As shown, the footplatecoupling portions 862 each includes a body 870 that defines a pair ofbores 874 that extend longitudinally through the body 870. The bores 874of both the first and second couplers 830, 834 are configured to receivethe locking mechanism 842. To couple the footplates to the distractor,the bores 864 of the first and second footplates 818, 822 are alignedwith the bores 874 of the first and second couplers 830, 834, and thepin 846 is inserted, such that a barrel 848 of the pin 846 passesthrough respective bores of the footplates 818, 822 and couplers 830,834.

As shown in FIGS. 10A and 10C, the third coupler 840 is attached to thedistractor body 826 at a location proximal from both the first andsecond couplers 830, 834.

As shown, in FIG. 10C, the third coupler 840 includes a distractorconnecting portion 878 for connecting the third coupler 840 to thedistractor body 826, and a coupling portion 882 for connecting the thirdcoupler to the locking mechanism 842 (i.e. the pin 846). In that regard,the coupling portion 882 also defines a pair of bores 886 that areconfigured to receive respective barrels 848 of the pin 846. Preferablythe bores 886 are slightly smaller in diameter than the bores 864, 874to create a greater frictional fit between the third coupling 840 andthe pin 846 than the fit between the bores 864, 874 and the pin 846. Thetight fit ensures that the pin 846 will not be removed unintentionally.

To decouple or otherwise release the footplates 818, 822 from thedistractor 814, the pin 846 is removed by pulling the end of the pin 846and disengaging the pin 846 from out of couplers 830, 834, and 840. Awire (not shown) may be attached to the pin 846 and brought through thepercutaneous incision to allow the locking mechanism 846 to bedisengaged from outside the patient. This may require, however awire-wrapping procedure that prevents the distractor from being able tobe disengaged prematurely. Accordingly, the third coupler 840 may alsoinclude bores 890 that extend through the coupling portion 882 above thebores 886. The wire may extend through the bores 890.

In another embodiment and in reference to FIGS. 11A-11C the distractorassembly may include couplers that have a locking mechanism incorporatedinto them. As shown in FIG. 11A, a distractor assembly 910 includes adistractor 914, a first footplate 918 releasably coupled to thedistractor 914, and a second footplate 922 releasably coupled to thedistractor 914 at a location distal to the first footplate 918. In theembodiment shown, the first footplate 918 is configured to translatewith respect to the second footplate 922.

As shown in FIG. 11A, the distractor 914 includes a body 926, a firstcoupling 930 translatably attached to the body 926, and a second coupler934 attached to a distal portion of the body 926. The distractor 914further includes an activation mechanism that extends into a channel ofthe body 926. The activation mechanism is configured to drive orotherwise translate the first coupler 930, and thus, the first footplate918.

As best shown in FIG. 11B the first and second couplers 930, 934 eachinclude a body 942 that defines a longitudinally extending bore orchannel 946 that extends through the body 942. The channel 946 isconfigured to receive the distractor 914. The body 942 further defines arecess 948 that extends up into a bottom surface of the body 942. Therecess 948 is configured to receive a raised geometry defined by thefootplates. Each coupler 930, 934 also includes a pair of spring fingers950 that extend down from a top portion of the body 942. As shown, aspring finger 950 extends from each lateral side of the body 942. Thebottom end of each spring finger 950 includes a laterally outwardextending foot 954. The spring fingers 950 and in particular the feet954 are configured to engage the first and second footplates 918, 922.

As best shown in FIG. 11C, each footplate 918, 922 includes a pair ofwings 958 extending outward from a central bridge portion 962. As shown,the central bridge portion 962 defines a raised geometry or protrusion966 and a pair of slots 970. As shown, a slot 970 is defined on eachlateral side of the raised protrusion 966. The raised protrusion 966 isconfigured to engage the recess 948 of one of the couplers 930, 934 tothereby prevent rotation of the footplates. The slots 970 are configuredto receive a foot 954 of a respective spring finger 950 to thereby lockthe footplate to the coupler. In this way, the spring fingers 950 may beconsidered a locking mechanism. Assembly is accomplished by the surgeonsnapping the couplers 930, 934 onto the detachable footplates 918, 922and then attaching the couplers 930, 934 to the distractor body 926.

Removal of the distractor 914 may be accomplished by making a secondincision to access the spring fingers 950. It is expected that thespring fingers 950 will be able to be squeezed with standard forcepsavailable in the operating room, to thereby release the couplers 930,934 from the footplates 918, 922. While a second incision is made, itmay be possible to remove couplers 930, 934 without making a secondincision. For example, a slidable tube may be used that is slid over thecouplers 930, 934 to force the fingers 950 laterally in and release thecouplers 930, 934 from the footplates 918, 922.

In another embodiment and in reference to FIGS. 12A-12E the distractorassembly may include a hollow locking pin to lock the footplates to thedistractor. As shown in FIG. 12A, a distractor assembly 1010 includes adistractor 1014, a first footplate 1018 releasably coupled to thedistractor 1014, and a second footplate 1022 releasably coupled to thedistractor 1014. In the embodiment shown, the first footplate 1018 isconfigured to translate relative to the second footplate 1022.

As shown in FIG. 12A, the distractor 1014 includes a longitudinallyelongate distractor body 1026, a first coupler 1030 translatablyattached to the body 1026, a second coupler 1034 attached to the body1026 at a location distal to the first coupler 1030, and a third coupler1040 attached to the body 1026 at a location proximal to the firstcoupler 1030. The first coupler is configured to releasably couple thefirst footplate 1018 to the distractor body 1026, while the secondcoupler is configured to releasably couple the second footplate 1022 tothe distractor body 1026. The distractor 1014 further includes anactivation mechanism for driving the first coupler 1030, and thus, thefirst footplate 1018 in a proximal direction. A locking mechanism 1042is configured to lock the first and second footplates 1018, 1022 to thefirst and second couplers 1030, 1034.

As shown in FIG. 12B, each footplate 1018, 1022 includes a centralbridge portion 1046 having a raised body 1050. As shown, the raised body1050 defines a bore 1054 that extends longitudinally through the body1050. Also shown in FIG. 12B, the first and second couplers 1030, 1034each include a footplate coupling portion 1058 that defines a bore 1062that extends longitudinally through the coupling portion 1058. Thecoupling portion 1058 further defines a recess 1066 that extends into abottom surface of the coupling portion 1058. The recess 1066 isconfigured to receive the raised body 1050 of one of the footplates suchthat the bore 1054 of the raised body 1050 aligns with the bore 1062 ofthe coupling portion 1058. The aligned bores 1054, 1062 are configuredto receive the locking mechanism 1042.

Referring to FIGS. 12A, 12C, and 12D, the third coupler 1040 includes acoupling portion 1072 that defines a bore 1076 that extendslongitudinally through the coupling portion 1072. As shown in FIG. 12D,the bore 1076 is slightly larger than the bores 1054, 1062 and defines arecess 1078 extending into the surface of the bore 1076. As shown inFIG. 12C, the bore 1076 is configured to receive the locking mechanism1042.

As shown in FIGS. 12C-12E, the locking mechanism 1042 includes alongitudinally elongate locking pin 1080, a removal actuator 1084 thatextends through a longitudinally extending bore 1088 of the locking pin1080, and a tube 1092 configured to lock the locking pin 1080 to thethird coupler 1040. As shown, the locking pin 1080 includes a couplingportion 1096 that extends through the bores 1062 of the first and secondcouplers 1030, 1034, and a locking portion 1100 that is disposed withinthe bore 1076 of the third coupler 1040. As shown in FIGS. 12E-12F, thelocking portion 1100 includes four deflectable fingers 1104 that deflectto pass into the bore 1076 of the third coupler 1040. Each finger 1104includes a protrusion 1108 that is configured to engage the recess 1078defined in the bore 1076 of the third coupler 1040.

The locking mechanism 1042 is assembled by passing the locking pin 1080through the bores 1054, 1062 of the footplates 1018, 1022, and the firstand second couplers 1030, 1034, and also through the bore 1076 of thethird coupler 1040. Once placed, the coupling portion 1096 of thelocking pin 1080 should be disposed within the bores 1054, 1062 of thefootplates and first and second couplers, while the locking portion 1100of the locking pin 1080 is disposed within the bore 1076 of the thirdcoupler 1040. At this point, the actuator 1084 is disposed within thebore 1088 of the locking pin 1080. The tube 1092 may then be slid overthe actuator 1084 and into the bore 1088 of the locking pin 1080 tothereby prevent the fingers 1104 from deflecting. At this point the tube1092 is in a locked position. When the tube 1092 is inserted theprotrusions 1108 of the fingers 1104 should engage the recess 1078 ofthe third coupler's bore 1076. This captures the locking pin 1080 withinthe third coupler 1040 and secures the footplates 1018, 1022 to thedistractor 1014. The tube 1092, which is preferably made from nitinol,is then axially retained on the actuator 1084 by crimping on a ferrule.

Removal of the distractor 1014 is accomplished by cutting off theferrule outside the patient's body, removing the tube 1092 to anunlocked position, and then moving (i.e. pulling) the actuator 1084which in turn pulls the locking pin 1080 out of the third coupler 1040.This then allows the couplers 1030, 1034 to separate from theirrespective footplates 1018, 1022. The distractor 1014 may then beremoved leaving the footplates behind.

In another embodiment and in reference to FIGS. 13A-13C, the distractorassembly may include first and second footplates that are integrated,and an activation mechanism that is releasably attached to the firstfootplate. As shown in FIG. 13A, a distractor assembly 1110 includes adistractor 1114, a first footplate 1118 coupled to the distractor 1114,and a second footplate 1122 translatably coupled to the first footplate1118. In the embodiment shown, the second footplate 1122 translatesrelative to the first footplate 1118.

As shown in FIGS. 13A and 13C, the first footplate 1118 includes acentral bridge portion 1126 having a longitudinally elongate body 1130.As shown, the body 1130 defines a bore 1134 that extends longitudinallythrough the body 1130. The bore 1134 is shaped to have at least one flatsurface 1138. In the embodiment shown, the bore 1134 has two opposingflat surfaces 1138. In this regard, the bore 1134 is said to have akeyed geometry.

The second footplate 1122 includes a central bridge portion 1142 havingan extension 1146 that extends proximally toward the first footplate1118. As shown in FIG. 13C, the extension 1146 is shaped to fit thekeyed geometry of the first footplate's bore 1134. In that regard, theextension 1146 has two flat sides 1150 and is configured to be receivedby the bore 1134 of the first footplate 1118. The extension 1146 furtherdefines a bore 1154 that extends longitudinally through the extension1146. The internal surface of bore 1154 defines threads. In this way theextension 1146 is considered to carry a threaded track.

As shown in FIG. 13A, the distractor 1114 includes an activationmechanism 1170 having a longitudinally elongate body 1174 connected toan activation worm 1178 by a coupling mechanism 1186 at the body's 1174distal end. The activation mechanism 1170 further includes a sleeve 1188that is translatable along the body 1174. The sleeve 1188 is configuredto lock the activation mechanism 1170 to the first footplate 1118 whenthe sleeve 1188 is in a distal first position, and release theactivation mechanism 1170 when the sleeve 1188 is in a proximal secondposition.

As shown in FIGS. 13A and 13B, the activation worm 1178 includes alongitudinally elongate distraction screw 1190 that extends into thebore 1154 of the second footplate 1122. The distraction screw 1190includes external threads that engage the internal threads of the bore1154. The activation worm 1178 further includes spring fingers 1194 atits proximal end that define a cavity 1200. Extending from the cavity1200 is a coupling mechanism 1204 that is configured to engage thecoupling mechanism 1186 of the body 1174.

In use the activation worm 1178 is inserted into the bore 1154 of thesecond footplate 1122. When the body 1174 is inserted into the cavity1200 and coupled to the activation worm 1178, and the sleeve 1188 is inits distal position, the spring fingers 1194 of the activation worm 1178engage a flange 1208 of the bore 1134 of the first footplate 1118 andare prevented from deflecting inwardly. Because the spring fingers 1194are prevented from deflecting inwardly the activation worm 1178 islocked to the first footplate 1118.

Activation of the distractor 1114 to thereby translate the secondfootplate 1122 relative to the first footplate 1118 is accomplished byapplication of torque to the body 1174 and in turn to the activationworm 1178. The second footplate 1122 translates because of the keyedrelationship between the second footplate's extension 1146 and the firstfootplate's bore 1134. Because the extension 1146 cannot rotate due tothe keyed configuration, it translates along the distraction screw 1190.While it is preferred that the keyed geometry be inherent to the shapeof the extension 1146 and the bore 1134, it is perceived that a pin/slotcombination could work as well.

Removal of the distractor 1114 is accomplished by sliding the sleeve1188 proximally and removing the body 1174 from the activation worm 1178so that the fingers 1194 of the activation worm 1178 are no longerprevented from deflecting. At this point, the activation worm 1178 maybe pulled out through the percutaneous incision leaving the remainder ofthe assembly behind.

In another embodiment and in reference to FIG. 14A-14F the distractorassembly may include an activation mechanism that is used as a lockingcomponent between the detachable footplates and the distractor body. Asshown, a distractor assembly 1210 includes a distractor 1214, a firstfootplate 1218 releasably coupled to the distractor 1214 and a secondfootplate 1222 releasably coupled to the distractor 1214 at a locationdistal to the first footplate 1218. In the embodiment shown, both thefirst and second footplates 1218, 1222 translate relative to each other.

As shown in FIGS. 14E and 14F each footplate 1218, 1222 includes acentral bridge portion 1226 having two spaced apart upwardly extendingprotrusions 1230. The upper ends of each protrusion 1230 define anoutward extending flange 1234. The protrusions 1230 are spaced such thata recess 1238 is defined between the two protrusions 1230.

As shown in FIGS. 14A-14F, the distractor 1214 includes a longitudinallyextending outer housing 1242, a longitudinally extending body 1246rigidly coupled to an interior of the housing 1242, and a barrel 1250for each footplate 1218, 1222 translatably disposed within a bore 1254of the body 1246. As shown, the bore 1254 is elongate in thelongitudinal direction and defines a slot 1258 through a bottom portionof body 1246 and extending longitudinally along the bore 1254. Eachbarrel 1250 includes an engagement portion 1262 disposed within the bore1254 and a protrusion 1266 that extends down from the engagement portion1262 and through the slot 1258. Each protrusion 1266 is configured toengage the recess 1238 of a respective footplate 1218, 1222. Eachengagement portion 1262 defines a longitudinally elongate bore 1270 thatextends through the engagement portion 1262 in the longitudinaldirection. The bores 1270 each define internal threads. The direction ofthe threads will determine the direction the barrels 1250 translate.

The distractor further includes an activation mechanism having anactivation worm 1274 that extends through the bores 1270 of the barrels1250. The activation worm 1274 includes external threads for engagingthe internal threads of the barrel bores 1270. The activation worm 1274also includes a coupling member 1278 extending from its proximal end. Asthe activation worm 1274 is rotated, the barrels 1250 will translate intheir respective directions.

The distractor 1214 further includes a pair of L-rails 1280 that aredisposed within the housing 1242 and around the body 1246. The L-rails1280 are elongate in the longitudinal direction and each include aninwardly extending flange 1284. The flange 1284 of the L-rails 1280 areconfigured to engage flanges 1234 of the footplates 1218, 1222 tothereby lock the footplates 1218, 1222 to the distractor 1214. TheL-rails 1280 are biased apart by a spring 1292 contained within thehousing 1242. Each L-rail 1280 includes a ramp 1300 at its proximal end.As shown, the ramps 1300 angle laterally outwards as they extenddistally in the longitudinal direction.

As shown in FIGS. 14C and 14D, the activation mechanism further includesa body 1304 for rotating the activation worm 1274. The body 1304longitudinally elongate and includes a coupling member 1312 at itsdistal end. The coupling member 1312 is defined as a cavity 1316 that isconfigured to receive the coupling member 1278 of the activation worm1274. As shown, the cavity 1316 defines an outer rim 1320 configured toride up the ramps 1300 of the L-rails 1280.

As best shown in FIG. 14D, the activation mechanism body 1304 getsinserted onto the activation worm 1274. As the activation mechanism body1304 is being placed, the rim 1320 of the activation mechanism body 1304rides up the ramps 1300 of the L-rails 1280 to thereby compress theL-rails 1280 together. When the L-rails 1280 are compressed thefootplates 1218, 1222 are coupled to the distractor 1214, as shown inFIG. 14E. Once coupled, the activation mechanism body 1304 may berotated to thereby translate the barrels 1250, and thus, the footplates1218, 1222 with respect to each other.

Once distraction is complete, removal is accomplished by loosening theactivation mechanism body 1304 from the activation worm 1274, whichcauses the L-rails 1280 to release from the footplates 1218, 1222, asshown in FIG. 14F. This in turn allows the distractor 1214 to be removedthrough the percutaneous incision.

In another embodiment and in reference to FIGS. 15A-15E the distractorassembly may include couplers similar to those described in reference toFIGS. 6A-7E, except that rotation of an activation mechanism locks thefootplates to the couplers. As shown, a distractor assembly 1410includes a distractor 1414, a first footplate 1418 releasably coupled tothe distractor 1414, and a second footplate 1422 releasably coupled tothe distractor 1414 at a location distal to the first footplate 1418.The footplates 1418, 1422 are similar to the footplates described inreference to FIGS. 5A-5C.

The distractor 1414 includes a longitudinally elongate body 1426, afirst coupler 1430 attached to the body 1426, and a second coupler 1434attached to the body 1426. The first coupler 1430 is configured toreleasably couple the first footplate 1418 to the body 1426, and thesecond coupler 1434 is configured to releasably couple the secondfootplate 1422 to the body 1426.

As shown in FIGS. 15C-15E, each coupler 1430, 1434 includes footplatecoupling portion 1438 and a distractor connecting portion 1442 rotatablycoupled to the footplate coupling portion 1438. The distractorconnecting portion 1442 defines a bore 1444 that is configured toreceive the body 1426. As shown, the bore 1444 and the body 1426 arekeyed such that when the body 1426 is rotated, the distractor connectingportion 1442 rotates. The distractor coupling portion 1442 furtherdefines an outwardly extending bulge 1445 and an inwardly extendingrecess 1446 that are each configured to interact with the footplatecoupling portion 1438.

The footplate coupling portion 1438 defines a longitudinally extendingflexible finger 1448 having a free end 1450 to allow the finger 1448 toflex. As shown in FIG. 15D, a protrusion 1454 extends down from a bottomsurface of the flexible finger 1448 proximate to the free end 1450 ofthe finger 1448. The protrusion 1454 is configured to engage a detentdefined in a footplate, such as the detent 604 defined in the bridgeportion 584 of the footplate 518. The footplate coupling portion 1438further includes opposing outwardly extending flanges 1458 that define aT-shape configured to engage the T-slot defined by a footplate, such asT-slot 600 defined by the footplate 518. While the footplate couplingportion 1438 is being slid into place, the flexible finger 1448 willflex up as the protrusion 1454 that extends down from the bottom surfaceof the finger 1448 is dragged across the upper surface of the footplatescentral bridge. Once the protrusion 1454 is positioned over the detent604, the finger 1448 will return to its normal position, thereby placingthe protrusion 1454 into the detent 604. At this point, the footplatesare loosely held to the respective coupler 1430, 1434.

To lock the footplates 1418, 1422 to the first and second couplers 1430,1434 the body 1426 is rotated 180 degrees to thereby rotate thedistractor coupling portions 1442 of the first and second couplers 1430,1434 to position the respective bulges 1445 over the fingers 1448 of thefootplate coupling portions 1438. The bulges 1445 will prevent thefingers 1448 from deflecting thereby locking the footplates 1418, 1422to the distractor 1414. Conversely, to unlock the footplates 1418, 1422the body 1426 is rotated 180 degrees so that the recesses 1446 arepositioned over their respective fingers 1448 to thereby allow thefingers 1448 to flex. To prevent this rotation from happening untilremoval, a resorbable screw 1460 is used to lock the distractor couplingportions 1442 and their respective footplate coupling portions 1438together.

As shown in FIGS. 15A and 15B, the distractor 1414 further includes anactivation mechanism 1470 configured to be coupled to the body 1426 witha third coupler 1474. The coupler 1474 allows the activation mechanism1470 to translate one of the footplates 1418, 1422 with respect to theother. When the distraction is complete, radial teeth 1478 defined atthe distal end of the activation mechanism 1470 are configured to engageradial teeth 1482 defined by the proximal end of the body 1426. Thisallows transmission of the torque to the body 1426 so that theresorbable screws 1460 may be broken to thereby rotate the distractorcoupling portions 1442 and allow the fingers 1448 to flex. Thedistractor 1414 is then pulled out of the detachable footplates 1418,1422 and through the percutaneous incision, leaving the footplates 1418,1422 behind in the patient.

In another embodiment and in reference to FIGS. 16A and 16B thedistractor assembly may include resorbable screws to lock the footplatesto the distractor. As shown, a distractor assembly 1510 includes adistractor 1514, a first footplate 1518 releasably coupled to thedistractor 1514, and a second footplate 1522 releasably coupled to thedistractor 1514 at a location distal to the first footplate 1518. Aresorbable screw 1526 is used to lock at least the second footplate 1522to the distractor 1514. Over the course of distraction andconsolidation, the resorbable screw 1526 will become weak enough toallow the distractor 1514 to be disengaged from the footplate 1522 bythe normal technique described.

In another embodiment and in reference to FIGS. 17A-17E, the distractorassembly may include a releasable stop that when released allows thefootplates to decouple from the distractor. As shown, a distractorassembly 1610 includes a distractor 1614, a first footplate 1618releasably coupled to the distractor 1614, and a second footplate 1622releasably coupled to the distractor 1614 at a location that is distalto the first footplate 1618. In the embodiment shown, the firstfootplate 1618 is configured to translate proximally relative to thesecond footplate 1622.

As shown in FIGS. 17A and 17B, the distractor 1614 includes alongitudinally elongate body 1626, and an activation mechanism 1630 thatextends into a longitudinally elongate channel 1634 defined by thedistractor body 1626. As best shown in FIGS. 17B and 17C, the distractorbody 1626 defines an opening 1638 at its distal end and a releasablestop 1642 that selectively opens and closes the distal opening 1638. Thedistractor body 1626 further defines a longitudinally elongate slot 1646that extends along a bottom portion of the distractor body 1626. Theslot 1646 is configured to receive and contain the first and secondfootplates 1618, 1622.

In the illustrated embodiment, the releasable stop 1642 is a hinged door1650 that is pivotable about a pivot 1654. As shown, the door 1650defines a locking mechanism receiving bore 1658 that is configured toreceive a locking mechanism. The bore 1658 is parallel to thelongitudinal direction when the door 1650 is at some angle relative tothe longitudinal direction. For example, as shown in FIG. 17B, when thedoor 1650 is angled toward the proximal end of the distractor the bore1658 is parallel to the longitudinal direction and capable of receivingthe locking mechanism.

The activation mechanism 1630 includes a flexible activation extension1662 and an activation worm 1666 that is configured to engage at leastone of the footplates to thereby translate at least one of thefootplates relative to the other upon activation of the activation worm1666.

As shown in FIGS. 17D-17E, the first footplate 1618 includes a pair ofwings 1670 that extend out from a central bridge portion 1674. Each wing1670 is substantially planar and includes a plurality of screw holes forreceiving bone screws therethrough to secure the wings 1670 to bone,with wings 1670 positioned adjacent to the bone surface. 1.3 mm or 1.5mm resorbable screws may be used for example to fasten the wings 1670 tothe bone. Central bridge portion 1674 includes a body portion 1680 thatdefines a longitudinally extending channel 1684. The channel 1684defines internal threads that are configured to engage threads definedby the activation mechanism 1630 such that when the activation mechanism1630 is rotated the first footplate will translate proximally. As shownin FIG. 17C, the body portion 1680 extends through the slot 1646 and iscontained within the channel 1634 of the body 1626. In this way thedistractor 1614 is considered to have a first coupler.

Similarly the second footplate 1622 includes a central bridge portion1690 and a wing 1694 extending laterally out from opposing sides of thecentral bridge portion 1690. As shown, the central bridge portion 1690includes a body portion 1696 that defines a longitudinally extendingchannel 1698 that is configured to receive the locking mechanism.

As best shown in FIGS. 17B and 17C, the distractor assembly 1610 furtherincludes a locking mechanism 1700 that is configured to extend through abore of the activation mechanism through the bores of the first andsecond footplates 1618, 1622 and through the bore 1658 of the hingeddoor 1650. In the illustrated embodiment, the locking mechanism 1700 isa tube 1704 that is made of a flexible material such as nitinol.

In operation, when the distractor 1614 is ready to be removed, the tube1704 is pulled proximally so as to disengage the tube 1704 from the bore1658 of the hinged door 1650. Once disengaged, the door 1650 is free toswing freely and reverse turning of the activation mechanism 1630 willtranslate the first and second footplates 1618, 1622 out of the distalopening 1638 of the distractor body 1626.

In another embodiment and in reference to FIGS. 18A-18B, the distractorassembly may include a releasable stop that defines a screw. As shown,the releasable stop may be a screw 1706 that is held in place by thetube 1704. The screw 1706 includes fingers 1708 that can deflect and beheld securely in openings in the side of the distractor body 1626. Whenthe tube 1704 is removed, the removable screw can disengage from thebody 1626 and fall out. To make sure that the screw is not left withinthe patient, the side of the screw 1706 is secured to the distractorbody 1626 by a wire or cable that allows the screw 1706 to follow thedistract body 1626 as it is pulled out of the patient.

In another embodiment and in reference to FIGS. 19A-19G the distractorassembly may include a distractor having additional features. As shown,a distractor assembly 1710 includes a distractor 1714, a first footplate1718 releasably attached to the distractor 1714 and a second footplate1722 releasably attached to the distractor 1714 distal to the firstfootplate 1718 and configured to translate relative to the firstfootplate 1718.

As shown, the distractor 1714 includes a first body portion 1726configured to releasably hold the first footplate 1718 and a second bodyportion 1730 configured to releasably hold the second footplate 1722. Inthe illustrated embodiment the second body portion 1730 and thus thesecond footplate 1722 is configured to translate relative to the firstbody portion 1726.

As shown, the first body portion 1726 includes a body 1734, and a track1738 that extends distally from the body 1734. The body 1734 defines alongitudinal channel 1740 that extends therethrough, a pair of grooves1742 defined in the exterior surfaces of the sidewalls that define thechannel 1740, and a ball detent 1742 that extends down toward the firstfootplate 1718. The ball detent 1742 is configured to engage the firstfootplate 1718 to thereby secure the first footplate 1718 to the firstbody portion 1726. In this way, the first body portion 1726 may beconsidered a first coupler for coupling the first footplate 1718 to thedistractor 1714.

The second body portion 1730 includes a body 1746 that defines a channel1750 extending therethrough and a pair of grooves 1742 that are definedin the exterior surfaces of the sidewalls that define the channel 1740.The body 1746 further includes a pair of spring fingers 1754 eachdefined in lateral walls of the channel 1750. The spring fingers 1754are configured to spring laterally inwards when the footplate is placedonto the second body portion 1730 and then engage the footplate 1722when the footplate is properly positioned. To prevent the spring fingers1754 from springing in, the second body portion 1730 includes a lockcomponent 1758 disposed within the channel 1750 that blocks the fingers1754. A spring 1760 prevents the lock component 1758 from deflectingproximally unless it intentionally pulled. When its time to remove thedistractor 1714, the lock component 1758 is pulled proximally therebyallowing the spring fingers 1754 to flex inward again and allowing thesecond footplate 1722 to disengage from the second body portion 1730. Inthis way, the second body portion 1730 may be considered a secondcoupler for coupling the second footplate 1722 to the distractor 1714.

As best shown in FIG. 19D, the track 1738 extends distally throughchannel 1750 of the second body portion 1730. The track 1750 includes aplurality of grooves that are configured to be engaged by an activationworm such that when the activation worm is rotated, the second bodyportion 1730 translates distally. The track 1738 further includes aplurality of teeth on disposed on side surfaces of the track that areconfigured to be engaged by a pair of ratchet tabs extending from thesecond footplate 1718 to thereby prevent reverse sliding of the movablefootplate.

As shown in FIGS. 19A-19D, the distractor 1714 further includes anactivation mechanism 1766 having an activation extension 1768 and anactivation worm 1770 that extends distally from the activation extension1768. As shown, the activation mechanism 1766 or at least the activationworm 1770 extends through the channel 1740 of the first body portion1726 and into the channel 1750 of the second body portion 1730. As shownin FIG. 19D the activation worm 1770 includes external threads thatengage the grooves of the track 1738. Both the activation extension 1768and the activation worm 1770 define a bore 1774 that extendslongitudinally therethrough. The bore 1774 is configured to receive aremoval actuator 1778 that extends completely through the activationmechanism 1766, through the lock component 1758 and out a distal end ofthe second body portion 1730. The actuator 1778 is configured todisengage the first and second footplates 1718, 1722 from the first andsecond body portions 1726, 1730, when the actuator 1778 is pulled.

As shown in FIGS. 19F-19H, the first and second footplates 1718, 1722each include a pair of wings 1782 separated by a central bridge portion1786. Each central bridge portion 1786 includes a pair of longitudinallyextending walls 1790 that define a channel 1794 configured to receive arespective body portion 1726, 1730. The central bridge portion 1786 ofat least the first footplate 1718 defines a recess 1796 within thechannel 1794 that is configured to receive the ball detent 1742 of theof first body portion 1726 to thereby hold the first footplate 1718 tothe first body portion 1726. The walls 1790 of the first and secondfootplates 1718, 1722 include engagement features 1798 that areconfigured to engage the grooves 1742 of the first and second bodyportions 1726, 1730 to thereby retain the distractor 1714. The springfingers 1754 of the second body portion 1730 sit outside the secondfootplate 1722 and prevent the distractor 1714 from being removed.

The walls 1790 of the first and second footplates 1718, 1722 includedistal and proximal sides 1802 that are angled. The angled sides 1802 ofthe first footplate 1718 allow the second body portion 1730 to easilyride over the first footplate 1718 during removal of the distractor1714.

To lock the first footplate 1718 to the first body portion 1726, thedistractor assembly 1710 includes a locking mechanism 1806 that definesa sleeve 1810 that is disposed about the activation extension 1768 andcoupled to the first body portion 1726. In particular, the sleeve 1810includes external threads 1814 that engage internal threads 1818 of thefirst body portion 1726. When engaged, the ball detent 1742 of the firstbody portion 1726 is prevented from disengaging from the recess 1796 ofthe first footplate 1718 thereby locking the first footplate 1718 to thefirst body portion 1726. It should be understood that the sleeve 1810may be considered an oversized tube.

To remove the distractor 1714 and leave the footplates 1718, 1722behind, the sleeve 1810 is disengaged or otherwise removed from thefirst body portion 1726 thereby allowing the ball detent 1742 todisengage from the recess 1796. Once the sleeve is disengaged, theactuator 1778 is pulled which in turn pulls the lock component 1758proximally to thereby allow the fingers 1754 to disengage from thesecond footplate 1730. At this point the first and second footplates1718, 1722 are released from the distractor 1714 and further pulling ofthe actuator 1778 pulls the distractor 1714 out of the patient while thefirst and second footplates 1718, 1722 remain behind. Because the secondbody portion 1730 can not be pulled through the first footplate 1718,the second body portion 1730 rides up the angled sides 1802 of the firstfootplate's central bridge portion 1786 as it is pulled proximally.

As shown in FIGS. 20A and 20B the distractor assembly 1710 may include acurved track 1850 that is curved along a specific radius, such as apredetermined radius. In this embodiment, the activation extension 1768,the activation worm 1770, the actuator 1778, and the sleeve 1810 aremade of a flexible material, or of a rigid material that is laser cut tobe flexible.

In another embodiment and in reference to FIGS. 21A-21I, the distractorassembly may include other configurations that release the footplatesfrom the distractor when a tube is removed. As shown, a distractorassembly 1910 includes a distractor 1914, a first footplate 1918releasably attached to the distractor 1914, and a second footplate 1922releasably attached to the distractor distal to the first footplate1918. In the illustrated embodiment, the first footplate 1918 isconfigured to translate relative to the second footplate 1922.

As best shown in FIGS. 21A-21I, the distractor 1914 includes a firstbody portion 1950 that is configured to releasably hold the firstfootplate 1918 and a second body portion 1954 that is distal to thefirst body portion 1950 and configured to releasably hold the secondfootplate 1922. As shown, the first body portion 1950 is elongate in thelongitudinal direction L and includes an elongate channel 1958 thatextends through the first body portion 1950 in the longitudinaldirection L.

An upper wall of the channel 1958 defines a spring finger 1972 that isconfigured to engage the first footplate 1918 to thereby couple thefirst footplate 1918 to the first body portion 1950. As best shown inFIG. 21C, the spring finger 1972 includes an upward extending protrusion1976 at its end. That is, the finger 1972 includes a protrusion 1976that extends vertically away from the central axis of the distractor1914. The finger 1972 is configured to spring out and engage the firstfootplate 1918 to thereby couple the first footplate 1918 to the firstbody portion 1950. In this way, the first body portion 1950 may beconsidered a first coupler for coupling the first footplate 1918 to thedistractor 1914.

As shown in FIGS. 21H and 21I, a proximal portion of the first bodyportion 1950 defines lateral ratchet tabs 1979 that are configured toengage teeth defined by an activation track. The ratchet tabs 1979prevent reverse sliding of the first footplate 1918. The proximalportion of the first body portion 1950 also includes a release clip 1980that forces the ratchet tabs 1979 outward during removal of thedistractor 1914.

The second body portion 1954 is also elongate in the longitudinaldirection L and includes a holding portion 1982 and an activation track1986 that extends proximally from the holding portion 1982. The holdingportion 1982 includes an elongate channel 1998 that extends through theholding portion 1982 in the longitudinal direction L. The channel 1998of the second body portion 1954 is aligned with the channel 1958 of thefirst body portion 1950. An upper wall of the channel 1998 defines aspring finger 2002 having an upward extending protrusion 2006 at itsend. That is, the finger 2002 includes a protrusion 2006 that extendsvertically away from the central axis of the distractor 1914. The finger2002 is configured to spring out and engage the second footplate 1922 tothereby couple the second footplate 1922 to the second body portion1954. In this way, the second body portion 1954 may be considered asecond coupler for coupling the second footplate 1922 to the distractor1914

The activation track 1986 of the second body portion 1954 extends outfrom the holding portion 1982 and is configured to extend through achannel defined by a lower portion of the first footplate's centralbridge portion. As shown in FIG. 21C, the activation track 1986 definesa plurality of grooves 2010 that are exposed to the channel 1958 of thefirst body portion 1950. The grooves 2010 are disposed along thelongitudinal length of the activation track 1986 and are configured tobe engaged by external threads defined by the activation mechanism.

As shown in FIGS. 21A-21I, the distractor 1914 further includes anactivation mechanism 2014 having an activation extension 2018, and anactivation worm 2022 that extends distally from the activation extension2018. Both the activation extension 2018 and the activation worm 2022define a longitudinally elongate bore 2024 that extend therethrough. Asshown in FIG. 21C, the activation worm 2022 extends into the channel1958 of the first body portion 1950 and engages the grooves 2010 definedon the activation track 1986. In particular, the activation worm 2022includes threads 2026 that engage the grooves 2010 of the track suchthat rotation of the activation worm 2022 causes the first body portion1950 and thus the first footplate 1918 to translate proximally.

As shown in FIG. 21C the distractor assembly 1910 further includes alocking mechanism 2030 that extends through the bore 2024 defined by theactivation extension 2018, and activation worm 2022, through the channel1998 of the second body portion 1954, and out the distal end of thedistractor 1914. The locking mechanism 2030 includes a tube 2034 and aremoval actuator 2038 that extends completely through the tube 2034. Asshown, a distal end and a proximal end of the actuator 2038 includes awidened portion 2042. The widened portions 2042 may be ferrules that arecrimped onto the actuator. To remove the tube 2034 from the actuator2038, the proximal ferrule 2042 is cut off, to thereby allow the tube2034 to be pulled proximally.

As shown in FIGS. 21F-21I, the first and second footplates 1918, 1922each include a central bridge portion 2042 and wings 2046 that extendlaterally out from the bridge portion 2042. Each central bridge portion2042 includes a body 2050 that defines a longitudinally extendingchannel 2054. The channels 2054 are configured to receive the first andsecond body portions 1950, 1954 of the distractor 1914. As shown in FIG.21I a lower portion of the first footplate's channel 2054 issubstantially rectangular and is configured to receive the activationtrack 1986 that extends from the second body portion 1954. Thisarrangement allows the first body portion 1950 to translate along thetrack 1986 along a predetermined line.

To release the footplates 1918, 1922 from the distractor 1914 the tube2034 of the locking mechanism 2030 is removed to thereby allow thespring fingers of the first and second body portions 1950, 1954 to flex.When the actuator 2038 is pulled proximally, the distractor 1914 will bepulled proximally along with the actuator 2038 leaving the footplates1918, 1922 behind.

In another embodiment and in reference to FIGS. 22A-22H the distractorassembly may include a locking component that locks the distractor tothe footplates. As shown, a distractor assembly 2110 includes adistractor 2114, a first footplate 2118 releasably coupled to thedistractor 2114, and a second footplate 2122 coupled to the firstfootplate 2118. In the embodiment illustrated, the first footplate 2118is configured to translate relative to the second footplate 2122.

As shown in FIGS. 22B-22D, the distractor 2114 includes a coupler 2126that is releasably coupled to the first footplate 2118. The coupler 2126includes a body 2130 that defines a T-slot 2134 along its bottomsurface. The T-slot 2134 is defined by two downward extending walls2138, each wall 2138 having a laterally inward extending flange 2142.The T-slot 2134 is configured to receive and hold a portion of the firstfootplate 2118. An upper portion of the coupler 2126 includes alongitudinally extending bore 2146. Below the bore 2146 is a clip 2150that extends proximally and is configured to clip onto an activationmechanism.

In this regard, the distractor 2114 further includes an activationmechanism 2160 that is configured to drive the first footplate 2118relative to the second footplate 2122. As shown, the activationmechanism 2160 includes an activation extension 2164 and an activationworm 2168 that extends distally from the activation extension 2164. Theworm 2168 includes external threads that are configured to engage atrack that extends from the second footplate. As shown in FIG. 21A, theclip 2150 of the coupler 2126 engages the activation worm 2168 when theactivation worm 2168 is fully inserted. This firmly secures theactivation mechanism 2160 to the coupler 2126. This also preventsinadvertent rotation under no load.

As shown in FIGS. 22C, 22G, and 22H, the first footplate 2118 includes acentral bridge portion 2170 and a wing 2174 that extends laterally outfrom each side of the central bridge portion 2170. As shown, the centralbridge portion 2170 includes a body 2178 that defines a channel 2182that extends therethrough. An upper wall of the channel 2182 defines aslot 2186 that extends along the entire length of the upper wall. Alower wall of the channel 2182 defines a ratchet tab 2190. The body 2178further defines opposing longitudinally elongate slots 2194 that areconfigured to be engaged by the flanges 2142 of the coupler 2126.

The second footplate 2122 includes a central bridge portion 2200 and awing 2204 that extends laterally out from opposing sides of the centralbridge portion 2200. As shown, the central bridge portion 2200 includesa track 2208 that extends distally through the channel 2182 of the firstfootplate 2118. In the illustrated embodiment the track 2208 is curvedalong a predetermined arc. As shown the track 2208 includes grooves 2212that are configured to be engaged by the activation worm 2168 such thatrotation of the worm 2168 causes the first footplate 2118 to translatealong the track 2208. A bottom surface of the track 2208 includesengagement features such as teeth 2228 that are configured to be engagedby the ratchet tab 2190 of the first footplate 2118 to prevent reversesliding of the first footplate 2118 after distraction.

To lock the distractor 2114 to the first footplate 2118, the distractorassembly 2110 includes a locking mechanism 2234. The locking mechanism2234 includes a sleeve 2238 that is disposed about the activationextension 2164 and defines external threads 2250. The locking mechanism2234 further includes a nut 2254 having internal threads 2258 thatengage the external threads 2250 of the sleeve 2238. Extending distallyfrom the nut 2254 is a locking component 2262 that is configured toengage and lock the first footplate 2118 to the coupler 2126. In theillustrated embodiment, the lock component 2262 includes a shaft 2266that extends distally from the nut 2254 and through the bore 2146 of thecoupler 2126. Extending distally from the shaft 2266 is an engagementfeature 2270 that defines a plate 2274 that is configured to engage thechannel 2182 of the first footplate 2118 and force the first footplate2118 against the coupler 2126 to thereby lock the first footplate 2118to the coupler 2126.

In operation, the locking mechanism 2234 may be in a first position inwhich the engagement feature 2270 is locking the first footplate 2118 tothe coupler 2126 as shown in FIG. 22E. To release the first footplate2118 from the coupler 2126, the sleeve 2238 is rotated thereby causingthe nut 2254 to translate distally. As the nut 2254 translates theengagement feature 2270 is also translated distally and disengages fromthe coupler 2126, as shown in FIG. 22F. At this point the footplates2118, 2122 are released from the distractor 2114 and the distractor 2114may be removed while the footplates 2118, 2122 remain behind.

The present inventions are illustrated by the description of severalembodiments. The present invention, however, is not limited to theparticular embodiments described herein. Rather the present inventionencompasses any combination of the features of any of the embodimentsand natural variations thereof, as will be understood by persons havingordinary skill in the art. Further while certain features are describedas being first and second, it should be understood that either of thefeatures may be considered first or second. For example, while thefootplates are described as first and second footplates having differentfeatures, it should be understood that either footplate could beconsidered the first footplate or second footplate. Further, while thedistractors have been described as forcing bone segments away from eachother, it should be understood that the distractor disclosed may also beconfigured for reduction (i.e. forcing the bone segments toward eachother).

What is claimed is:
 1. A bone distractor assembly configured to distractfirst and second bone segments that are separated by a bone gap, thedistractor assembly comprising: a first footplate; a second footplateincluding an extension that carries a track; and a distractor releasablycoupled to the first footplate, the distractor including i) anactivation worm configured to engage the track, such that rotation ofthe worm causes the second footplate to translate relative to the firstfootplate, and ii) a sleeve having a distal coupling portion configuredto releasably lock the activation worm to the first footplate.
 2. Thedistractor assembly of claim 1, wherein the activation worm defines aconical head having external threads.
 3. The distractor assembly ofclaim 1, wherein (i) the distractor further includes a body disposedwithin the sleeve, the body being coupled to the activation worm, and(ii) the distal coupling portion of the sleeve defines external threadsthat are configured to engage internal threads defined by the firstfootplate to thereby releasably lock the activation worm to the firstfootplate.
 4. The distractor assembly of claim 1, wherein the first andsecond footplates are resorbable.
 5. The distractor assembly of claim 1,wherein the track defines a plurality of grooves.
 6. The distractorassembly of claim 5, wherein the first footplate includes a laggingratchet tab that is configured to engage the grooves.
 7. The distractorassembly of claim 1, wherein the first footplate includes a pair oflagging ratchet tabs that are configured to engage opposing lateral sidesurfaces of the second footplate's extension.
 8. The distractor assemblyof claim 1, wherein the extension has a key relationship with the firstfootplate such that rotation of the activation worm causes the secondfootplate to translate distally.
 9. The distractor assembly of claim 8,wherein the track defines a threaded bore that is configured to receivethe activation worm.
 10. The distractor assembly of claim 9, wherein theactivation worm, includes an elongate screw having external threads, andat least one spring finger extending proximally from the elongate screw,the spring finger configured to engage a flange defined by the firstfootplate.
 11. The distractor assembly of claim 10, wherein the couplingportion of the activation mechanism prevents the spring finger fromdeflecting to thereby lock the activation worm to the first footplate.12. The distractor assembly of claim 11, wherein the activation wormincludes four spring fingers that are configured to engage the flangedefined by the first footplate.